Froth flotation of oxidized iron ores with sulfonated oils



& ASSORI'ING SOUDS Patented Jan. 21, 1947 FROTH FLOTATION OF OXIDIZED IRON ORES WITH SULFONATED OILS Robert B. Booth, Springdale, and Earl C. Herkenhofl", Stamford, Conn., assignors to American Cyanamid Company, New York, N. Y., a corporation of Maine No Drawing. Application February 10, 1944, Serial No. 521,868

8 Claims. 1

This invention relates to a process of beneflciating iron ores. More particularly, the invention relates to those processes of iron ore beneflciation by froth flotation in which sulfonated saponiflable oils are used as promoting reagents.

The beneflciation of iron ore by froth flotation has presented a number of peculiarly diilicult practical problems. Naturally-occurring high grade ores have kept the unit value at a low figure. Economic considerations have, therefore, required a beneflciated concentrate to contain a high content of iron and that the recovery be fairly high. While it is a comparatively simple matter to concentrate certain iron ores by froth flotation with a number of different promoters of the anionic-type, such as oleic acid and the like, the results obtained have not been within an economically competitive range.

Rapidly diminishing sources of available high grade ore, particularly in the United States, have recently created increasin interest in beneficiating low grade iron ores by froth flotation. It is therefore a principal object of the present invention to develop such a process which will permit the production of concentrates in a sufficiently high grade and recovery to be advantageously compared with naturally-occurring ores. At the same time it is also desirable that the process be one which is simple in operation, low in cost and makes use of readily available reagents.

In general, according to the present invention, these objects are accomplished by conditioning low grade iron ores with a sulfonated saponifiable oil and an acid having a dissociation constant greater than 10". For best results an accessory oiling agent, preferably an unsulfonated oil, is usually helpful. The conditioned ore is then subjected to froth flotation in a conventional procedure.

Throughout the specification and claims the term sulfonated oils is used in the ordinary commercial sense to designate the products obtained by treating a saponifiable oil with a sulfonating agent, usually strong sulfuric acid. Consequently, it is quite possible that the products may be either sulfonated or sulfated or both. There is no intention that the term "sulfonated oils" shall be restricted to include only those compounds in which the sulfur is present in the form of sulfonic acid groups.

Commercially acceptable results are not ordinarily obtainable without an acid treatment of the ore except possibly in those cases in which the sulfonated oil reagent is very highly sulfonated. Such cases are actually not an exception since such promoters are usually either sufliciently acid in themselves to produce the necessary number of available H+ ions or contain sufficient residual acid from the sulfonating operation to furnish the necessary acidity. Apparently the acid treatment produces some change in the nature of the mineral surfaces. The exact nature of this surface change is not wholly understood and it is not meant that the present invention be limited to any particular theory of operation. It does appear to be necessary that the oil be sulfonated and that sufficient acid be used during the ore treatment to produce a pH of less than seven.

It is an advantage of the present invention that the particular acid from which the H+ ions are derived does not appear to be critical except that results of practical utility in general are not obtained when using weaker acids than those having a dissociation constant of 10- It is, of course, necessary that the acid anion should not have a depressive action on the iron minerals as is the case with tannic acid and the like. Sulfuric acid gives as good results as any and because of its availability and relatively low cost is probably preferable in practical operation. It is, however, not superior to other strong acids in the quality of the results obtained and the choice is based on the dictates of economics and not because of the similarity of the sulfate anion to the sulfonate or sulfate groups on the promoter.

It is also an advantage of the present invention that it is not limited to any particular ore. The froth flotation process of the present invention produces excellent results with the more common iron minerals such as hematite and magnetite. However, other iron minerals such martite, limonite, siderite, goethlte and the like which are commonly present in iron ores also may be 3 successfully floated by the procedure of the present invention. Taconite ores are amenable to treatment by the present process. The present process is not only capable of beneficiating nat- 4 about 60-70%. The conditioned pulp was then diluted to about 20-22% solids and subjected to froth flotation in a Fagergren type flotation machine. Unless otherwise noted, the rougher conurally-occurring, low-grade ores which are too 5 centrate was subjected to one cleaner flotation low in iron for blast furnace feed and which without additional reagents. In the tabulated cannot be beneficiated readily by washing and results which are given, the degree of sulfonasimilar operations, but will also produce comtion is indicated by listing the parts of sulfomercially acceptable concentrates from tailings nating agent per 100 parts of oil. Unless otherrejected in ordinary beneficiating processes in wise noted, any excess acid was not neutralized. common use. In some instances commercially available prepa- While commercially acceptable results may be rations were used and their source is indicated. obtained in many cases in the operation of the process of the present invention without the use EXAMPLE 1 of an accessory oiling agent. in most cases a def- A number of samples of a Minnesota iron ore inite improvement in both recovery and grade is washer plant reject, assaying about 14.5% iron obtained when one is used. Preferably, therefore, and containing principally hematite and quartz an oiling agent such as an unsulfonated oil is with small amounts of limonite, were tested usused. These oils may be either unsaponifiable ing different sulfonated oils. The efiect of these mineral oils or hydrocarbons or saponifiable oroils was tested using a sulfonated oil alone, with ganic oils. In some cases the sulfonated reagent sulfuric acid, with an accessory oiling agent, an itself may have sufficiently oily characteristics or unsulfonated oil, and finally with both the acid may contain a sufficient amount of oil as a diland the accessory oil. Illustrative results are uent therewith so that the use of additional oiling shown in Table 1.

Table 1 Promoter used a if is Concentrate g fig Sulfonation A i t b A oflu d P t l D5356, H4804 23 et-2:51: ol1 e;pe1 -;c e r 1't pH new asset 1 100 10 5.25 None None 40.40 79.91 3.57 6.0 133 13 as et "235 100 10 5.26 2.10 2.32 57.16 55.15 6.90 2.5 100 4.20 None None 47.04 92.00 1.27 4.1 Do 100 I 30 4.20 None 3.48 51.65 95.48 0.69 100 30 4.20 2.10 None 54.43 91.07 1.21 100 30 4.20 2.10 3.48 58.02 70.49 4.75 2.6 100 3.16 None None 39.11 86.36 2.07 4.1 Do 100 50 3.10 None 4.04 46.70 90.51 1.15 100 50 3.16 2.10 None 55.55 87.52 1.58 100 12 .5512 .52: 222 as 2a at's.ittzsf'it-t ilttdi 1: 5 1: N03: 11;; a 255g :13; Cyanmld 2114 2.14 4.48 52.57 04.73 0.21 2.0

agents may be unnecessary. Such cases, however, are ordinarily the exception rather than the rule, and require higher amounts of promoter. Since in most cases the promoter is more expensive than an oil, such use ordinarily is not to be preferred.

The process of the present invention behaves normally with respect to slimes in the ore. Like many common anionic flotations a small amount of slime can be tolerated but increasing amounts generally produce corresponding decreases in the grade of the concentrate and increases in the amount of reagents required. It is therefore desirable to deslime the feed fairly thoroughly although the extreme degree of desliming essential with many cationic flotations is unnecessary.

The invention will be described in greater detail in connection with the following examples which are meant to be illustratve only and not by way of limitation. All parts are by weight unless otherwise noted. In these examples a similar mechanical procedure was followed throughout. The ore was ground to about minus 28 mesh, if necessary, and then deslimed by hydraulic classification. The deslimed ore was then conditioned with the flotation reagents including the sulfonated oil, the acid and the oiling agent when one is used. Unless otherwise noted, the conditioning step is carried out at high solids,

From these results it will be seen that the sulfonated oils when used alone produced a quite satisfactory recovery but that the beneficiation, 50 particularly in the case of the sulfonated castor oil, was not wholly satisfactory. The addition of fuel oil to the circuit caused, in certain cases, an immediate improvement in the grade, but, in general, did appear to exert an appreciable effect 65 on the recovery. The use of the sulfonated oil with acid but no oiling agent, on the other hand, produces an improved grade in all cases. The optimum combination from the practical point of view, was that of sulfonated oil, acid and oiling agent, and this gave a very high grade even though the recovery was ordinarily somewhat less than when the sulfonated oil was used alone. This was because some of the iron in this ore was present as relatively low grade middlings. The variations in the degree of sulfonation show that it is not particularly critical over a very wide range, but that in general less promoter is required when employing a highly sulfonated reagent. EXAMPLE 2 In order to show the wide variety of oils which may be sulfonated to produce suitable reagents for use according to the present invention, a number of samples were treated using different 7 suli'onated products. Some of the products were uvul U11 llU'Ull Distribu- 'p oentFe 54 7 31 777 1 1 720255531902 %%%M%N%B%W.MM%MNMW%%HM 786 878778 8 87867878877878 Iron concentrate per cent tio Conditioning and flotat1on, pounds per ton Sullo- Dated H230 product stituent of the sulfonated product contains at least one aliphatic group having twelve or more carbon atoms. It is also quite apparent that these need not be pure in the sense that they are free from other constituents, nor need they be used alone since it is quite apparent that the mixed oils, both natural and artificial, produce equally acceptable results. It will be noted that the sulfonated products in neutralized or unneutralized orm as well as the salts of the sulfonated products, which are precipitated from aqueous solution or dispersion by the addition of an appropriate metallic salt, are also useful promoters.

Table 2 Sulfonation Lvq; u 1,.

sulfonated for use in these tests, others were commercially available preparations. In the first 26 tests, a Minnesota ore washer reject assaying about iron, containing chiefiy hematite and some limonite in a silica gangue, was used. In the th to 44th tests a composite of washer plant rejects from the treatment of Minnesota ores was used. This composite assayed about 22% iron. In the remaining tests a washer reject similar to that used in Example 1 was 10 f treated. The results are shown in Table 2. In all tests the pH of the rougher tailings ranged from 2.5 to 3.0.

EXAMPLE 3 In order to illustrate the wide limits of the 0 acids which can be used to provide the necessary H+ ions during the beneficiation operation, various sulfonated oils and a variety of added acid reagents were employed on a number of samples of iron ore. All the ore samples used were low grade, those used in the first 19 tests assaying about 25% Fe, and those in the remaining tests assaying about 14.5% Fe. The results are shown in Table 3.

glyc- ,mannitol, sorbitol and the like. In each case, however, it will be noted that the non-polar con- It is apparent that the oils which can be sulfonated to produce effective promoting reagents in the acid circuit of the present invention include a wide variety of materials. They appear 6 to have one common characteristic, all are saponifiable oils. It will be seen that the materials include such a wide variety of esters as ethyl oleate, the methyl ester of talloel, fatty acid esters such as the oleate, laurate, and ricinoleate of polyhydroxy alcohols such as the glycols,

erin

Table 3 Sulfonation Conditioning and flotation Iron concentrate Rougher 011 used Lbs./tn Acid Addition agents Assay Dismhq tailing Parts suli'oem went pH H s 0 nated gs Typo Parts product Type Lbs/ton Type Lbs/ton e e Cottonseed. 100 60 2.1 5. 2 Cottonseed oil 4.1 55. 0O 82. 91 2. 3 Do... 60 2.1 5. 2 Talloel 4.2 54.86 81.88 2.3 60 2. l 3. l Bunker C fuel oil. 4. 2 52. 71 85. 01 2. 5 60 2.1 3.1 OIei'c acid 4. 2 54. 46 84. 31 60 2. 1 3. 2 Naphthenlc acid. 4. 3 50. 95 84. 17 60 2.1 3. 2 Crude oil 4. 2 51.63 87. 35 co 2. 1 3 2 Lauryl mercaptan... 4. 2 55. 54 7B. 99 6O 2. 1 3. 2 Talloel methyl ester. 4. 2 51. 22 85.66 2. 7 60 2.1 3. 2 Fuel oil N0. 2 4. 2 54.05 81. 62 2. 8 60 2.1 5.2 do 4.2 55.54 79.18 2.6 67 l. 6 4. 1 Keryl chloride. 4. 1 56. 89 81. 73 2. 2 G7 1. 5 5.1 Fuel oil No. 2 4.1 53. 83.39 3. 9 67 1.8 2.3 Bunker C fuel oil... 4.7 51.46 80.92 50 1.8 2. 3 Fish oil 4. 7 56.82 90.00 2 7 50 1. 8 2. 3 Coconut oil. 4. 7 59. 36 80. 87 2. 7 60 2. l 3. 2 Fuel oil No. 2 4. 2 56.08 82. 3O 2. 6 60 2. l 1. 6 d 4. 2 57. 96 85.41 3. 2 6O 2. l Formic 3. 2 4.2 56.62 77. 72 60 2. 1 p-i'loluene sul- 8. 4 4. 2 52. 10 83. 68 2. 6

mm. 2.1 Sul|ui'ic 2.1 4.5 52. 57 94.73 2.9

2.1 None 4. 5 14. 82 95. 50 6. 9 2.1 Sulfui'ous.. 6. 3 4. 5 52. 69 90.70 29 2. l H yd rofluoric. 2. 1 4. 5 55. 01 92. 08 3. 3 2.1 B0ri c 5.3 4. 5 14.13 94. 01 6. 9 2.1 Citric.. 3.2 4. 5 55. 70 70. 21 3. 9 2. l Caigbgnic satur- 4. 5 21. 08 85. 30 6. 2

EXAMPLE 4 A series of tests similar to that of Example 3 was made on a number of samples of the same ore (assaying 14.5% Fe) used in the latter part or that example. In each case, 2.1 lbs/ton of an oil sulfonated by treatment with 60% by weight of 95.5% sulfuric acid and 4.2 lbs/ton of fuel oil were used. Instead of adding acid per se, a number of acid salts were used. It was found that substantially any strongly acid salts can be used provided the anion is a constituent of an acid having a dissociation constant greater than 10- and the salts have no deleterious effect on the flotation of the iron minerals. Illustrative results are shown in Table 4.

Table 4 lronconccntrate Acidic material per cent Fe Rough or tail- SulIonated oil used Type Lbs/ton Assay Cottonseed Rice bran.

Sodium ehlorosul- 2. 6

innate.

Sodium fiuorosilicate.

Potassium bisul- 2. 6

late.

EXAMPLE 5 Two samples of the same ore used in the latter part of Example 3 and in Example 4 were treated using as reagents 1.64 lbs/ton of neutralized sulfonated castor oil. 2 lbs/ton of sulfuric acid and 3.52 lbs/ton of fuel oil. The first sample was conditioned at solids and then diluted to flotation density, the second was conditioned at flotation density. The rougher concentrate was cleaned once in the first test and twice in the second test. The results are shown in Table 5.

The superior results obtained by conditioning at high solids at. clearly shown.

EXAMPLE 6 A number of samples of the same iron ore used in Example 5 was treated using difierent degrees of desliming. The promoter used was a neutralized sulfonated castor oil, Aquasol AR-QO, (American Cyanamid Company). Illustrative results are shown in the following table.

Table 6 ore was then diluted to 22% solids and subjected to froth flotation, the rougher concentrate being Lbs lton used cleaned twice without additional reagents a d th Amy Per cleaner tailings being combined. The results are Per- Product con; :2; 8111101- F' 5 Shown m Table Fc distrib. H250 i cagitlor oil Table 7 Essentially deslimed 10 Assay Per cent Product Per-cent distrib. Cale. head 100.00 14.43 100 00 weght Per cent Percent of Fe Slime..." 6.04 23.85 9. 95 Fe insol Clean. conc. 22.54 52.36 81.49 1.64 2.00 3. 52 Clean. tail 7.72 4.00 2.49 Rgh. t 11L...... 03.70 1.38 6.07 Caleheaduu 100.00 14.25 l00.00 15 Prim. slime 5.22 25.97 9.52 Par/ rally Sec. slime 1. S4 25. 76 3. 33 dESIlmEd glean. CO1; 21. 90 53. 42 82. 13 can.ta1 13.01 1.27 1.16 Cale. hcad 100.00 14. 41 100.00 R Slime 3'76 29.89 7 80 gh. 1110-..... 58.03 .05 3.86 Clean. cone. 22. 42 53.00 82.46 1.92 2. 00 4.40 glelant. 111.. 0.0; 3.02 31 c a1 1.1 1.10 .93 b Companson of the results in Examples 6 and 7 NO! show that at least a partial desliming is highly decai 14,65 10000 sirable but that the grade and recovery per so all *3- i- 2.74 2.50 11.00 are not appreciably increased by further treat- R011. mu... 63:81 3100 10.40 ment. A comparison of the reagent consumption 0 in Example 7 with the last test in Example 6 shows a tremendous decrease in reagent consumption. I These savin s combined with the advanta es from It W111 be noted that a fairly good cleaner conh g g t e increased grade and/or recovery often warcentrate was obtained even in the sample which 0t d n d t n d that ther was very rant the use of the additional deslimmg opera- Y n 65 a a i an e tions in combination with scrubbing or polishing. little difierence in grade and recovery between the I n d d d u d s ed Sam f deslred, the ore may be scrubbed and then deessen y an par la y 8 mm slimed or, as above, may be deslimed followed by pies. A comparison of the reagent consumptmn scrubbing and further desnmmg shows the advantage of desliming, the consumpt1on being decreased as the degree of the deshm- EXAMPLE 8 mg is increased.

EXAM LE 7 In order to show the utility of mixed sulfonated oils or mixtures of sulfonated oils with other sul- 40 fonated materials, a number of samples were An additional sample of the same ore used in treated with such mixtures. Illustrative results Example 6 was subjected to both desliming and are shown in Table 8. In the first two tests the scrubbing. The ore was first deslimed by hysame ore used in the first tests of Example 2 was draulic classification at about 25% solids and the employed. In the remaining tests a beneficiasands scrubbed for several minutes in a Fagergren tion plant reject assaying about 15% Fe was used.

Table 8 Conditioning and flotation Iron concentrate Assay Fuel Distrib., Sulionated product H18 0 on per cent Per cent Per cent Fe Fe insol.

Mixture of oleic acid 1 part, peanut oil 1 part; com- LIL/i071. LIL/011 LIL/ton mercial preparation (sulionated) 2. 4 2. 4 4.8 57.62 10.88 77. 44 A leather conditioning oil: Hydrogenated fish oil 4 parts, oleic acid 2 parts, peanut oil 2 parts, tallow 2 parts; commercial preparation (sulfonated). 2.5 2. 5 5.0 69.18 10.00 80.80 Sulionated castor oil 1 part (Aquasol All-00) Petronate 1 part (oil-soluble petroleum sulfonatc 1. 75 2. 3 4.1 60. 53 6. 66 96. 17

S nnebom Sons) Sulionated castor oil 1 part (Aquasol Alt-90). SP-702 1 part (water-soluble petroleum sullonat 1. 40 2. 3 3.1 60.31 7. 48 96.04 S *1 gistrtibutolri, t 11 0118. e 088 0101 par l i f 8 2; t fi sb 2.33 2.3 4.1 00.03 0.72 96.46

PM 0610801 pars I A. 1 mm on mm H180 2.33 2.3 4.1 58.83 9.48 90.42

70 flotation machine with the air intake closed. The EXAMPLE 9 scrubbed sands were deslimed and conditioned at about 70% solids with 0.93 lbs/ton of the sulfonated castor oil, 2.0 lbs./ton of sulfuric acid and A number of different iron ore samples were treated using different sulfonated oils in order to illustrate the versatility of the present process.

2.20 1bs./ton of 22% B. fuel oil. The conditioned Illustrative results are shownin Table 9.

Table 9 Sullonation Concentrate gfig Lbs/ton used Oil used Assay H so Per cent Assay 2 4. Der P o- Fu 1 P t P t r pH Type Parts m ter oil l g $52 1? 6 Fe Castor, commercial preparation Aquasol A R-90 (American Cyanamid Co.) 2.00 2. 61 4.13 61.16 7. 46 91. 22 3.92 2. 7

DESCRIPTION or Ones Usnn Anovn 1st test-Washer tailing containing chiefly hematite, limonite and 2nd test-re containing hematite, siderite, and goethite; assaying 3rd testA taconite; assaying 22% Fe.

4th test-0re containing martite; assaying about 22% Fe.

th test-Ore containing magnetite; assaying about 21% Fe.

quartz; assaying about Fe. about 16% Fe. 30%

All concentrates were cleaned once, except in the last two tests where two cleanings were employed.

In the claims, the term oxidized iron ores is used in its commonly accepted meaning to include not only iron oxide ores such as those containing magnetite, hematite, etc., but also hydroxides, carbonates, etc.

We claim:

1. A method of beneficiating oxidized iron ores by froth flotation which comprises subjecting the ore to froth flotation in the presence of an effective amount of a collector containing as its essential collecting constituent a sulfonated saponiflable organic oil, characterized by the presence of an aliphatic group having at least twelve carbon atoms, and an effective amount of an acid substance, the anion of which is a constituent of an acid having a dissociation constant greater than whereby a concentrate relatively rich in iron mineral and a tailing relatively poor in iron is obtained.

2. A method according to claim 1 in which the sulfonated oil collecting agent is associated with at least one oiling agent selected from the group consisting of unsulfonated saponifiable oils, unsulfonated hydrocarbon oils and unsulfonated fatty acids.

3. A method of beneflciating oxidized iron ores by froth flotation which comprises subjecting the ore to froth flotation in the presence of an eflective amount of a collector containing as its essential collecting constituent a sulfonated saponiflable organic oil of the fatty acid-glyceride type, characterized by the presence of an aliphatic group having at least twelve carbon atoms, and

an efiective amount of an acid substance, the 55 anion of which is a constituent of an acid having a. dissociation constant greater than 10-",

whereby a concentrate relatively rich in iron mineral and a tailing relatively poor in iron is obtained.

4. A method according to claim 3 in which the sulfonated saponifiable oil is fish oil.

5. A method according to claim 3 in which the sulfonated saponifiable oil is soy bean oil.

6. A method according to claim 3 in which the sulfonated saponifiable oil is corn oil.

7. A method of beneficiating oxidized iron ores by froth flotation which comprises conditioning the ore at high solids with a reagent containing as its essential collecting constituent a sulfonated saponifiable organic oil, characterized by the presence of an aliphatic group having at least twelve carbon atoms and an effective amount of an acid substance, the anion of which is a. constituent of an acid having a dissociation constant greater than 10 diluting the conditioned ore to flotation density and subjecting it to froth flotation to produce a. concentrate relatively rich in iron mineral and a tailing relatively poor in iron.

8. A method of beneficiating oxidized iron ores by froth flotation which comprises conditioning the ore at high solids with a reagent containing as its essential collecting constituent a sulfonated saponifiable organic oil, characterized by the presence of an aliphatic group having at least twelve carbon atoms and an efiective amount of sulfuric acid, diluting the conditioned ore to flotation density and subjecting it to froth flotation to produce a. concentrate relatively rich in iron mineral and a tailing relatively poor in iron.

ROBERT B. BOOTH. EARL C. HERKENHOF'F. 

